<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://cdn.jsdelivr.net/npm/vue@2.6.10/dist/vue.js"></script>
    <style>
        .one {
            width: 100px;
            height: 100px;
            background-color: yellow;
        }
        .two {
            width: 200px;
            height: 200px;
            background-color: hotpink;
        }
        .three {
            width: 250px;
            height: 250px;
            background-color: red;
        }
        .active {
            color: skyblue;
        }
    </style>
</head>

<body>
    <div id="app">
        <div :class="className">aaa</div><br/>
        <div :class="{active:isShow}">bbb</div>
        <div :class="isShow ? 'active' : ''">ccc</div>
    </div>
    <script>
        Vue.config.productionTip = false;
        const vm = new Vue({
            el: "#app",
            data() {
                return {
                    // class强制绑定写法允许是一个对象写法,对象的key就是类型,如果这个key对应的value是truthy的值,则这个类开启
                    className: {
                        one: false,
                        two: true,
                        three: true
                    },
                    isShow: true
                }
            }
        })
</script>
</body>

</html>